Table 4.
Effect of previous mood episodes and illness duration as predictors of likelihood of recovery and time until recovery after adjusting for clinical covariates
| Covariates | b | Wald | OR | (95% CI) | p | Δ R 2a |
|---|---|---|---|---|---|---|
| Previous depressive episode models | ||||||
| Logistic regression: predicting recovery | ||||||
| Depressive episodes | 0.75 | 4.74 | 2.12 | (1.08–4.16) | 0.030 | 0.07 |
| Control variables | ||||||
| Illness duration | 0.75 | 4.17 | 2.11 | (1.03–4.33) | 0.041 | 0.05 |
| Age at onset | 0.78 | 4.51 | 2.18 | (1.06–4.49) | 0.034 | 0.06 |
| Number of manic episodes | 0.89 | 4.03 | 2.46 | (1.02–5.91) | 0.045 | 0.07 |
| Lifetime anxiety disorder | 0.72 | 3.98 | 2.05 | (0.31–1.68) | 0.046 | 0.05 |
| Number of anxiety disorders | 0.66 | 3.36 | 1.94 | (0.96–3.94) | 0.067 | 0.06 |
| Number of co-morbid conditions | 0.78 | 4.86 | 2.17 | (1.09–4.33) | 0.027 | 0.06 |
| All covariates togetherb | 0.72 | 3.27 | 2.05 | (0.94–4.47) | 0.071 | 0.06 |
| Cox regression: predicting time until recovery | ||||||
| Depressive episodes | 0.43 | 5.06 | 1.53 | (1.06–2.22) | 0.024 | 0.05 |
| Control variables | ||||||
| Illness duration | 0.32 | 2.72 | 1.38 | (0.94–2.03) | 0.099 | 0.07 |
| Age at onset | 0.40 | 4.14 | 1.50 | (1.02–2.20) | 0.042 | 0.05 |
| Number of manic episodes | 0.29 | 1.29 | 1.33 | (0.81–2.19) | 0.256 | 0.07 |
| Lifetime anxiety disorder | 0.37 | 3.47 | 1.44 | (0.98–2.12) | 0.062 | 0.05 |
| Number of anxiety disorders | 0.33 | 2.76 | 1.39 | (0.94–2.06) | 0.097 | 0.05 |
| Number of co-morbid conditions | 0.43 | 4.78 | 1.53 | (1.05–2.24) | 0.029 | 0.05 |
| All covariates togetherb | 0.10 | 0.15 | 1.11 | (0.65–1.88) | 0.704 | 0.09 |
| Previous manic episode models | ||||||
| Cox regression: predicting time until recovery | ||||||
| Manic episodes | 0.55 | 5.06 | 1.73 | (1.07–2.78) | 0.025 | 0.06 |
| Control variables | ||||||
| Illness duration | 0.51 | 4.37 | 1.67 | (1.03–2.69) | 0.037 | 0.08 |
| Age at onset | 0.54 | 4.93 | 1.72 | (1.07–2.77) | 0.026 | 0.06 |
| Number of depressive episodes | 0.47 | 3.49 | 1.61 | (0.98–2.64) | 0.062 | 0.07 |
| Lifetime anxiety disorder | 0.48 | 3.74 | 1.62 | (0.99–2.63) | 0.053 | 0.06 |
| Number of anxiety disorders | 0.47 | 3.57 | 1.60 | (0.98–2.60) | 0.059 | 0.06 |
| Number of co-morbid conditions | 0.55 | 5.00 | 1.73 | (1.07–2.78) | 0.025 | 0.06 |
| All covariates togetherb | 0.42 | 2.54 | 1.52 | (0.91–2.54) | 0.111 | 0.09 |
| Illness duration models | ||||||
| Cox regression: predicting time until recovery | ||||||
| Illness duration | −0.02 | 6.29 | 0.98 | (0.97–0.99) | 0.012 | 0.06 |
| Control variables | ||||||
| Age at onset | −0.02 | 5.35 | 0.98 | (0.97–1.00) | 0.021 | 0.06 |
| Number of manic episodes | −0.02 | 4.08 | 0.99 | (0.97–1.00) | 0.043 | 0.08 |
| Number of depressive episodes | −0.02 | 4.05 | 0.99 | (0.97–1.00) | 0.044 | 0.07 |
| Lifetime anxiety disorder | −0.02 | 6.95 | 0.98 | (0.97–1.00) | 0.008 | 0.07 |
| Number of anxiety disorders | −0.02 | 6.68 | 0.98 | (0.97–1.00) | 0.010 | 0.07 |
| Number of co-morbid conditions | −0.02 | 6.35 | 0.98 | (0.97–1.00) | 0.012 | 0.06 |
| All covariates togetherb | −0.02 | 4.88 | 0.98 | (0.97–1.00) | 0.027 | 0.09 |
OR, Odds ratio; CI, confidence interval.
R2 for logistic regressions represents Nagelkerke R2, an estimate of the increment in variance in the probability of recovery accounted for by the predictors tested. R2 for Cox regressions represents Cox–Snell R2, an estimate of the relative association between survival and the predictors tested.
All covariates denote a model where all covariates listed above for a given model were entered as a set of variables into the model. Covariates were added first individually to examine the effect of each covariate, and then added as a group of covariates to test their combined effect.